Cytomegalovirus (CMV) can be devastating in the patient who has undergone an allogeneic bone marrow transplant. Rapid detection of CMV infection in these patients can be life-saving, allowing the prompt administration of anti-CMV drugs. There is also a clinical need for a quantitative measure of the CMV present in the clinical specimen to allow for monitoring therapy and predicting emergence of drug-resistant variants. A research assay has been developed by a commercial vendor allowing the use of quantitative polymerase chain reaction (PCR) to measure the CMV DNA extracted from whole blood. We will evaluate this PCR assay by using peripheral blood leukocytes collected by American Medical Laboratories and compare the results with the CMV antigenemia quantitative assay (performed at American Medical Laboratories) that detects the presence of CMV pp65 early structural protein in polymorphonuclear leukocytes and monocytes.